SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '249a09b2d7827eb7a6124ce7b0eb5dfec0974a97d7d3c36bb65116213f04525f' 
  AND token = '2/CvSz81hptpZrbhDxfBi6I+IhnHGs3WlsywcxuZAXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}